Time dependent-temperature independent color changing label

ABSTRACT

A timing device for indicating a passage of a duration of time is disclosed. The timing device in accordance with the embodiments of the invention has a grid array architecture. The grid array architecture includes an electrode structure with an anode layer, a cathode layer and a thermistor layer. The anode layer and the thermistor layer are electrically coupled through a plurality of cathode trace structures. In operation the timing device is actuated through a suitable mechanism to initiate depletion of the anode layer and, thereby, indicate a passage of a duration time. As the anode layer depletes, sequential cathode trace structures are exposed and the thermistor layer acts as a temperature dependent resistor through a plurality of exposed cathode trace structures.

RELATED APPLICATION(S)

This Patent Application is a continuation-in-part of the co-pending U.S.patent application Ser. No. 11/902,728, filed Sep. 21, 2007 and entitled“TIMING SYSTEM AND METHOD FOR MAKING THE SAME,” which is acontinuation-in-part of the U.S. patent application Ser. No. 10/865,724,filed Jun. 9, 2004 and entitled “TIMING SYSTEM AND DEVICE AND METHOD FORMAKING THE SAME,” now issued as U.S. Pat. No. 7,372,780 which is acontinuation-in-part of the U.S. patent application Ser. No. 10/376,672,filed Feb. 26, 2003 and entitled “TIMING SYSTEM AND DEVICE AND METHODFOR MAKING THE SAME,” now issued as U.S. Pat. No. 6,822,931 B2, which isa continuation-in-part of the U.S. patent application Ser. No.10/319,233 filed Dec. 13, 2002, and entitled “TIMING SYSTEM AND DEVICEAND METHOD FOR MAKING THE SAME,” now issued as U.S. Pat. No. 6,801,477B2. This Patent Application also claims priority under 35 U.S.C. section119(e) to the co-pending U.S. Provisional Patent Application, Ser. No.61/155,850, filed Feb. 26, 2009 and entitled “TIME DEPENDENT-TEMPERATUREINDEPENDENT COLOR CHANGING LABEL.” The co-pending U.S. ProvisionalPatent Application, Ser. No. 61/155,850, filed Feb. 26, 2009, andentitled “TIME DEPENDENT-TEMPERATURE INDEPENDENT COLOR CHANGING LABEL,”the co-pending U.S. patent application Ser. No. 11/902,728, filed Sep.21, 2007 and entitled “TIMING SYSTEM AND METHOD FOR MAKING THE SAME,”and the U.S. Pat. Nos. 7,372,780, 6,822,931 B2 and 6,801,477 B2 are allhereby incorporated by reference.

FIELD OF THE INVENTION

The invention relates to timing systems and devices and a method formaking the same. More specifically, the invention relates to systems anddevices for and methods of indicating the passage of a duration time.

BACKGROUND OF THE INVENTION

There are a number of different timing systems and devices, generallyreferred to as time-temperature indicators (TTIs), which can be used tomonitor the exposure of objects to a range of temperatures over aspecified period of time. In an early example, Witonsky, in U.S. Pat.No. 3,942,467, describes a time-temperature indicator with anencapsulated inner container and a pH sensitive dye solution containedtherein. The device of Witonsky further has an encapsulated outercontainer containing an organic material which undergoes solvolysis. Theouter container and the inner container are separated by a membrane.When the membrane between the inner container and the outer container isbroken, the contents of the containers mix and over a period of timechange color, thus providing an indication of the passage of a durationof time. A number of other time-temperature indicators utilize wickingtechniques (such as described in U.S. Pat. No. 5,709,472 and U.S. Pat.No. 6,042,264, both issued to Prusik et al.) or diffusion layertechniques (such as described in U.S. Pat. No. 4,629,330 issued toNichols and U.S. Pat. Nos. 5,930,206 and 5,633,835 both issued to Haaset al.). In U.S. Pat. No. 6,198,701 issued to De Jonghe et al., anelectrochemical timing device is described, whereby consumption of anelectrode is used to provide an indication of the passage of a durationof time.

Time-temperature indicators can have a number of different applicationsfor indicating when an event or activity needs to take place. Forexample, time-temperature indicators have applications for indicatingwhen the perishable materials have expired and need to be thrown out.Time-temperature indicators also have applications for general inventorymanagement, for monitoring projects, activities and a host of other timeand/or temperature dependent events. Therefore, there is a continuedneed to develop reliable timing systems and devices which can be usedfor a variety of different applications.

SUMMARY OF THE INVENTION

The present invention is directed to a device and system for indicatingthe passage of a duration of time and a method of making the same.While, the present invention is referred to herein as a timing device,it is understood that the timing device of the present invention canalso be sensitive to temperature. While a timing device, in accordancewith the embodiments of the invention, can be configured to be more orless sensitive to temperature, the timing device will generally react,or change, at a faster rate at higher temperatures unless the timingdevice is configured with a temperature compensating element, such asdescribed in detail below.

A timing device, in accordance with the embodiments of the presentinvention is a chemical-based timing device, electrochemical-basedtiming device, or a combination thereof. The timing device, whenactuated, provides a visual indication of a passage of time. The timingdevice is configured as a “stand alone” indicator or, alternatively, isconfigured to be coupled with any number of circuits which also providean audible signal or otherwise sense and/or store information regardingthe operation of the device.

In some embodiments, the device comprises a lens, a base and means foraltering the visibility of the base through the lens and therebyindicating the passage of a duration of time. In some embodiments, themeans for altering the visibility of the base through the lens comprisesan optical medium positioned between the lens and the base. The opticalmedium comprises chemicals and/or elements of a battery that react orotherwise change over time and, thereby alters the visibility of thebase through the lens. For example, one or more of the materials, layersor components of the optical medium are converted from opaque totransparent or, alternatively, from transparent to opaque, therebyincreasing or decreasing the visibility of the base through the lens,respectfully. Alternately, one or more of the materials, layers orcomponents of the optical medium are dissolved or depleted, therebyaltering the visibility of the base through the lens.

In accordance with the embodiments of the invention, the optical mediumcomprises a solid layer positioned between the lens and the base, alsoreferred to herein as a lens coating layer, and a fluid layer positionedbetween the solid layer and the base. The fluid layer contains gel,water and any suitable chemical(s) required to change the solid layerfrom opaque to transparent, change the layer from transparent to opaque,deplete the solid layer or dissolve the solid layer, as explained indetail below. In some embodiments of the invention, the solid layer isopaque and when the device is actuated, the fluid layer dissolves thesolid layer over a duration of time, thereby making the base visiblethrough the lens and indicating the passage of a duration of time.

In further embodiments of the invention, a timing device comprises anindicator between the lens and the lens coating layer to enhance thevisual indication of the passage of time. Suitable indicators are fluidsor solid, and can include, but are not limited to pH indicators andreactive dye indicators, which generate a color change when reacted withthe fluid layer, after the fluid layer sufficiently depletes ordissolves the lens coating layer. Alternatively, the lens coating layeris a semi-porous membrane layer, wherein the indicator provides a colorchange when a sufficient amount of the reactive species from the fluidmedium migrates through the membrane layer.

In still further embodiments of the invention, a timing device comprisesa battery, wherein at least a portion of the optical medium between thesolid layer and the base actively participates in an electrochemicalprocess resulting in a visual change indicating the passage of aduration of time. In accordance with this embodiment of the invention,the battery is a galvanic cell and the optical medium comprises anelectrolyte. A galvanic cell is a battery where reduction and oxidationof species within the battery will occur spontaneously as long as thereis a conductive path from a first electrode of the cell to a secondelectrode of the cell. In operation a material within the electrolyte isplated between the base and the lens, thereby reducing the visibility ofthe base through the lens. Alternatively, an opaque electrode positionedbetween the lens and the base is depleted, thereby increasing thevisibility of the base through the lens.

In still further embodiments of the invention, the battery is anelectrolytic cell. An electrolytic cell requires a current from anotherbattery, or other current source, to drive the reduction and oxidationof species within the battery. In accordance with this embodiment, acurrent from an external battery, or current source, flows through thebattery and a material within the electrolyte is plated out between thelens and the base, thereby reducing the visibility of the base throughthe lens. Alternatively, an opaque electrode positioned between the lensand the base is depleted, thereby increasing the visibility of the basethrough the lens.

Regardless of whether a timing device is configured to operate as agalvanic cell or as an electrolytic cell, the timing device can comprisea colored electrolyte. In accordance with the embodiments of theinvention, the colored electrolyte becomes visible after depleting oneor more electrode materials positioned between a transparent lens andthe colored electrolyte, thereby indicating the passage of a duration oftime. For example, a timing device comprises a clear lens formed from apolymer, such as polyester. The polyester lens is coated with a firstelectrode material, such as aluminum. The timing device furthercomprises a base structure with a second electrode material. The secondelectrode material is able be any metal with a reduction potential thatis different from a reduction potential of the first electrode material.If the device is being operated as an electrolytic cell, as explainedabove, then the reduction potential of the first electrode material andthe second electrode material is able to be the same. Between the firstelectrode material and the base structure is the colored electrolyte andwhen the device is activated, the first electrode material is depletedfrom the transparent lens and the colored electrolyte becomes visible,thereby indicating the passage of the duration of time.

In accordance with further embodiments of the invention, a timing deviceis configured with a lens structure and/or the base structure formedfrom a conductive polymer with an electrode material coated thereon. Theconductive polymer is believed to help ensure uniform plating and/ordepletion of electrode materials when the device is activated, such asdescribed in detail above. Alternatively, or in addition to the use of aconductive polymer, as described above, a metal screen is able to be incontact with, or imbedded in, one or more of the electrode materials tohelp ensure uniform plating and/or depletion of electrode materials.

In still further embodiments of the invention, a timing device isconfigured to operate as an electrochemical cell and includes anelectrolyte with an indicator. For example, the timing device comprisesan electrolyte with a pH indicator that changes color when theelectrochemical cell is activated, such as described above, and theelectrochemical cell generates a sufficient concentration of an ion or apH altering species within the electrolyte.

A timing device, in accordance with the embodiments of the invention, isactuated using any number of different mechanisms or combination ofmechanisms. For example, where the timing device is a chemical-basedtiming device, the timing device is formed in parts, wherein a firstpart comprises a first reactive region and a second part comprises asecond reactive region. To form an activated device, the first part andthe second part are brought together and the first reactive region andthe second reactive region are held eclipsed and in contact.Alternatively, a chemical-based timing device comprises a membrane or aremovable structure separating the reactive regions of the device,wherein the membrane is broken or the structure is removed to activatethe device.

In some embodiments, where the timing device is an electrochemical-basedtiming device, the device is actuated by a switch mechanism that closesa circuit between electrode elements of a galvanic or an electrolyticcell. Alternatively, the device is fabricated in parts as describedabove, wherein the parts have contact features, which when broughttogether close a circuit between the electrode elements of a galvanic oran electrolytic cell. An actuator switch, in accordance with furtherembodiments of the invention, is in electrical communication with athermosensor, wherein the thermosensor instructs the actuator switch toclose a circuit between electrode elements of a galvanic or anelectrolytic cell within a range of temperatures.

In accordance with yet further embodiments of the invention, a timingdevice and system comprises a photo-sensitive component, element orfilm. For example, a timing device comprises a piece of photographicfilm, which is color film, black and white film or a combinationthereof. The photographic film is formed from a base with a photographicmedium coated or deposited thereon, wherein the photographic film iscapable of being activated to change color or shade and thereby indicatethe passage of a duration of time. The photographic material is anyphotographic medium, but in some embodiments comprises a silver-basedmaterial including, but not limited to, silver chloride, silverfluoride, silver iodide and/or combinations thereof. In yet otherembodiments of the invention the photographic medium comprises asilver-soap (Ag⁺ cations in a fatty acid such as stearic acid) oftenused in thermally-activated films. Where the photographic medium is asilver halide, the silver halide is mixed with a binder, such ascellulose or gelatin, to hold the silver halide material on the base.

The photographic material, in accordance with the embodiments of theinvention, is made to be thermally and/or light sensitive using anynumber of techniques known in the art, including the addition of sulfurand gold and/or a dye, such as an infrared absorbing dye. To activatethe photographic medium a developer is applied to the film. There are anumber of materials that is able to be used for developing photographicmaterials, such as hydroquinone-based developers. Generally, alldevelopers contain chemicals that assist in the reduction of silverhalide or silver cations to form a darkened or colored image.

In accordance with the embodiments of the invention, a developer isincorporated into the construction of the film and a timing device isthermally activated or is activated by removing a barrier between thephotographic material and the developer. Alternatively, the photographicmaterial and the developer are included on separate parts or regions ofa timing device and are activated by bringing together a part or regionof the film with the photographic material with a part or region of thefilm with the developer.

In accordance with yet further embodiments of the invention, a devicecomprises a film with zones that change color at different rates and,therefore, provide an indication of the passage of a range of times.Each of the zones comprises a photographic material, as explained above,or other chemical and/or electro-chemical materials that can beactivated to change color at different rates. When the zones comprisephotographic materials, the zones are made to have different reactionrates by using photographic materials with different sensitivities toheat, light and/or developer, and/or by varying the thickness ofdiffusion layers deposited over the zones. In accordance with furtherembodiments of the invention, the zones are made to have different ratesof reaction and/or sensitivity to a developer by pre-treating the zonesto a range of different light and/or heat exposures, wherein the zoneswith longer exposures will develop and change color faster than zoneswith shorter exposures.

A system, in accordance with the embodiments of the invention, comprisesa timing film, such as described above, and further comprises anadhesion layer for attaching pieces of film to consumer articles, suchas containers of leftover food. In some embodiments, the system alsocomprises a dispenser for conveniently dispensing pieces of film from astack or roll of the timing film and means, such as a magnet, forattaching the dispenser to a household appliance.

In accordance with the embodiments of the invention, a timing devicecomprises an electrochemical structure, such as described above, that iscapable of being activated and configured to generate an audio and/orvisual response to indicate passage of a duration of time after beingactivated. In some embodiments, the timing device also comprises acompensating element such as a varistor, a thermistor and/orcombinations thereof. The compensating element is electrically coupledto the electrochemical structure and regulates the time for the responsewith respect to changes in temperature.

In still further embodiments of the invention, a timing device comprisesan electrochromic structure configured to generate a visual indicationin a prescribed period of time after being activated. In someembodiments, the timing device also comprises a driver circuit. Thedriver circuit is electrically coupled to the electrochromic structureand is configured to actuate electrochromic structure in the prescribedperiod of time. The driver circuit is able to include a timing circuitand a battery structure. Further, the timing circuit is able to beprogrammable to generate a visual indication in a range of prescribedperiods of time. Also, the timing device is able to include zones whichare each configured to indicate a passage of a different andpredetermined duration of time.

In accordance with yet further embodiments of the invention, a timingdevice comprises an electrochemical structure and an indicating layer.In some embodiments, the electrochemical structure comprises anindicating electrolyte, a top electrode and a bottom electrode with theindicating layer proximal with the top electrode. In operation, the topand the bottom electrodes are electrically coupled and the top electrodeis depleted or partially depleted, allowing the indicating electrolyteto come into contact with the indicating layer and thus generate avisual indication of the passage of time.

In accordance with still further embodiments of the invention, a timingdevice comprises electrodes that sandwich a solid-state electrolyte.Suitable solid-state electrolytes include, but are not limited to,silver halide (e.g. AgI and RbAg₄I₅), silver selenide (e.g. Ag₂Se),sodium ion complexes (e.g. sodium β-Aluminum and NASICON), lithium ioncomplexes (e.g. LiCoO₂, LiNiO₂ and LiMnO₂), oxides (e.g cubic stabilizedZrO₂, β-Bi2O₃, and defect Perovskites) and Fluoride ion complexes (e.g.PbF₂, BaF₂, SrF₂ and CaF₂). In accordance with these embodiments,depletion or partial depletion of at least one of the electrodesprovides or initiates a visual indication of a passage of a duration oftime, such as described in detail above. The timing device can alsoinclude a switch mechanism, a compensating element and/or an indicator,such as a pH indicator, also described in detail above. In yet furtherembodiments, the timing device includes a plurality of sub-cells orzones that collectively provide a visual indication of a passage of arange of durations of time.

In accordance with a method of the invention, a timing device is formedin parts, such as described with reference to FIGS. 3A-C. For example, afirst electrode structure is formed on a first piece of a substrate anda second electrode structure is formed on a second piece of a substrate,wherein at least one of the first electrode structure and the secondelectrode structure comprises a solid-state electrolyte. In operationthe first electrode structure and the second electrode structure areconfigured to contact each other in a sandwich-like configuration tothereby actuate the timing device and provide a visual indication of apassage of a duration of time. The substrates can be formed from anynumber of different materials or combinations of materials includingglass, metal, plastic and combinations thereof. In some embodiments, thesubstrates are formed from plastic, such as polyester or another similartransparent material. In accordance with yet further embodiments of theinvention, a removable protective layer is formed over the firstelectrode structure and the second electrode structure and is removedprior to placing the first electrode structure and second electrodestructure in contact with each other.

In accordance with yet further embodiments of the invention, a timingdevice has what is referred to herein as a grid array architecture. Inaccordance with this embodiment, a suitable electrolyte is formed orplaced on a suitable base material. Over, and in contact with theelectrolyte an anode layer, such as aluminum is formed. A cathode layerconfigured as traces of an array and made up of a dissimilar metal, suchas copper, is formed, on top of and in contact with the aluminum layer.In some embodiments, the cathode layer is not in direct contact with theelectrolyte, being blocked by the anode layer, while the anode layer isin direct contact with the electrolyte. A thermistor layer is formedcoincident with the cathode layer and in electrical series with thecopper cathode. An array of cathode trace structures are formed over andin electrical contact with the anode layer. The anode layer, the cathodelayer, the thermistor layer, the cathode trace structures and thecontact trace are formed using any suitable technique known in the artincluding, but not limited to, vapor deposition, sputtering andmicro-printing techniques.

A timing device with a grid array architecture preferably includes amechanism for activating the timing device, such as described above andbelow. When the timing device is activated the anode layer begins todeplete in a direction away from the cathode trace, thereby exposingsequentially positioned cathode trace structures. Newly exposed cathodetrace structures provide points of unequal electrical potential causingcurrent to flow. As anode material depletes away from the newly exposedtrace, distance between the leading edges of each increases, whichincrease resistance and decreases rate of depletion until a new cathodetrace is exposed once again. Distances between cathode array tracescontrols the overall rate that the anode layer is depleted. The number,the spacing, the thicknesses and geometries of the cathode tracestructures, as well as the thickness of the anode layer, the cathodelayer and thermistor layer, are designed or tailored for the applicationat hand. Further, the material used to form the thermistor layer, inaccordance with the embodiments of the invention, is selected toregulate the overall depletion rate of the anode and temperatureindependence.

In still further embodiments of the invention, a timing device comprisesan anode layer, a cathode layer and an electrolyte attached to asuitable lens and base layer, such as described above. In accordancewith some embodiments, the anode layer and the cathode layer arepositioned adjacent to one another along the longitudinal axis of thetiming device. In this embodiment, the anode layer extendslongitudinally in a direction away from the cathode layer. When thetiming device is activated, the anode layer is depleted at a pointnearest to the cathode layer first and progresses in a longitudinaldirection away from and perpendicular to the cathode layer. The timingdevice expires when the anode layer is fully depleted. This is anexample of a one-cell device. In some embodiments, the timing devicecomprises multiple anode depletion patterns or cells that are depletedas the anode layer is depleted. In such a case, the total depletion timeof the device equals the sum of depletion times of each individual cell.In some embodiments, the electrolyte has a relatively high resistivityvalue to achieve a longer expiration time of the timing device. In someembodiments, the electrolyte has a relatively smaller resistivity valueto achieve a shorter expiration time of the timing device. In someembodiments, the timing device further comprises a temperaturecompensating element, such as a thermistor or a temperature dependentresistor. In these embodiments, the temperature compensating element hasa temperature curve which inversely matches the temperature curve of theremainder of the cell in its entirety or partially matched which wouldresult in a temperature curve as requested by a user. Consequently, asthe temperature of the operating environment changes, the depletion rateof the anode layer either remains constant or varies with externaltemperature, depending upon the embodiment of the device.

In yet further embodiments of the invention, a timing device comprises acathode array architecture such as described above. In accordance withthis embodiment, a timing device comprises an anode layer and anelectrolyte attached to a suitable lens and base layer and a pluralityof cathode trace structures that are reintroduced throughout the timingdevice. In this embodiment, the anode layer extends longitudinally in adirection away from each cathode trace structure. When the timing deviceis activated, the anode layer is depleted at a point nearest to thefirst cathode trace structure and progresses in a longitudinal directionaway from and perpendicular to each cathode trace structure. The timingdevice expires when the anode layer is fully depleted. In someembodiments, the plurality of cathode trace structures are reintroducedat evenly spaced intervals throughout the timing device. In someembodiments, the cathode trace structures are reintroduced at unevenlyspaced intervals throughout the timing device. In these embodiments, thecathode trace structures are spaced such that there is an accelerationof the depletion of the anode layer as the device nears expiration. Insome embodiments, the lens of the timing device comprises multiple anodedepletion patterns printed onto the lens that are uncovered as the anodelayer is depleted.

A system in accordance with some embodiments comprises a cathode arrayarchitecture with a lens and base, such as described above and furthercomprises an adhesion layer attached to the base. In this system, thebase is adhesive backed with a pressure sensitive adhesive or otheradhesive suitable for attaching the system to an article.

A timing device with a cathode array architecture is activated when theelectrical circuit becomes complete. In some embodiments, the externalelectron path is left in the open position. In these embodiments, theexternal electron path can be set into the closed position by a user orby an automated means during manufacturing. Once the electron path isclosed the device is activated and the electrochemical process begins.In some embodiments, the electron path of the timing device ismanufactured in a closed position, but the electrolyte is only partiallydeposited. In these embodiments, an electrolyte is partially depositeduntil just short of contacting the cathode layer. The timing device isfurther manufactured with a quantity of electrolyte contained within aprotective reservoir, wherein the protective reservoir is molded intothe cathode layer and protrudes outward. In this embodiment, the timingdevice is activated when a user applies pressure to the reservoirthereby breaking the protective barrier and allowing the small quantityof electrolyte to contact the main body of the previously depositedelectrolyte. Consequently, the electrolyte contacts the cathode layer,the circuit is completed and the timing device is activated.

BRIEF DESCRIPTION OF THE DRAWINGS AND ATTACHMENTS

FIGS. 1A-B show a schematic representation of a timing device, inaccordance with the embodiments of the invention.

FIG. 2 shows a schematic representation of a timing device, inaccordance with an embodiment of the invention.

FIGS. 3A-C show systems for assembling timing devices, in accordancewith the method of the present invention.

FIGS. 4A-C show schematic cross sectional views of several timing deviceconfigurations, in accordance with the embodiments of the invention.

FIG. 5 shows a piece of timing film with a plurality of zones forindicating the passage of a range of times, in accordance with theembodiments of the invention.

FIG. 6 is a cross-sectional representation of a section of timing film,in accordance with the embodiments of the invention.

FIGS. 7A-B show schematic cross-sectional views of timing deviceconfigurations with compensator elements, in accordance with theembodiments of the invention.

FIG. 8A shows a reversible reaction sequence for an electrochromicmaterial used in a timing device, in accordance with the embodiments ofthe invention.

FIG. 8B shows a multi-layer construction for an electrochromic device,in accordance with the embodiments of the invention.

FIGS. 9A-B show a timing device with a timer circuit, in accordance withthe embodiments of the invention.

FIG. 10 shows a schematic representation of a timing device comprisingan indicating electrolyte and an indicating layer, in accordance withthe embodiments of the invention.

FIG. 11 shows a schematic representation of a timing device comprising asolid-state electrolyte, in accordance with the embodiments of theinvention.

FIG. 12 shows a schematic representation of a timing device comprising asolid-state electrolyte, in accordance with further embodiments of theinvention.

FIG. 13A-B show schematic representations of a timing device with a gridarray architecture, in accordance with further embodiments of theinvention.

FIG. 14 shows a timing device with multiple anode depletion patterns inaccordance with some embodiments of the invention.

FIG. 15 shows a timing device with grid array architecture in accordancewith some embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 1A-B, a timing device 100, in accordance with theembodiments of the invention is a chemical-based timing device, anelectrochemical-based timing device, or a combination thereof. Thetiming device 100 comprises a transparent lens 101, a base 105 and anoptical medium 103 therebetween. When the device 100 is actuated, theoptical medium 103 is changed to a modified medium 103′, therebyaltering the visibility of the base 105 through the lens 101 indicatingthe passage of a duration of time. The lens 101 and base 105 are formedfrom any suitable material, or combination of materials, including, butnot limited to polymers and plastic materials.

Still referring to FIGS. 1A-B, the optical medium 103 comprises anynumber of different chemicals or elements which over the duration oftime alter the visibility of the base 105 through the lens, as explainedin detail below. In some embodiments, however, the base 105 becomes morevisible through the lens 101 when the device 100 has expired. In orderto enhance the visibility of the base 105 through the lens 101, when thedevice 100 has expired, the base 105 is brightly colored and/or hasindicia printed thereon, such that the bright color and/or the indiciaare visible through the lens 101 when the device is expired.

Referring now to FIG. 2, in accordance with some embodiments of theinvention, a timing device 200 comprises a lens 201, a base 211 and anoptical medium 204, as described above. In some embodiments, the opticalmedium 204 comprises a fluid layer 207. The fluid layer 207 can becomprised of any number of fluid materials, but in some embodimentscomprises a transparent gel material, which is either acid or basic andwhich is either conductive or insulating, depending on the applicationat hand. In some embodiments, the optical medium 204 also comprises anopaque layer 205, also referred to herein as a lens coating layer, whichdoes not imply that the opaque layer 205 is necessarily coated directlyon the lens 201. The lens coating 205 is formed from a material whichwill react with the fluid layer 207, when the device 200 is activated.For example, the lens coating layer 205 is formed from a hardened gel,such as gelatin and thiosulfate. In some embodiments, the liquid layer207 dissolves the lens coating layer 205 when the device 200 isactivated, thereby increasing the visibility of the base therebelow andindicating the passage of a duration of time.

Still referring to FIG. 2, in further embodiments of the invention, atiming device 200 comprises an activation layer 203. The activationlayer 203 comprises an indicator, such as a pH indicator which reactswith the fluid layer 207, when the fluid layer 207 sufficiently depletesor dissolves the lens coating layer 205. Alternatively, an indicator isincorporated into the lens coating layer 205 and is dissolved or leachedby the fluid layer 207, such that when the concentration of theindicator in the fluid layer 207 becomes sufficiently high, the fluidlayer 207 changes color.

In still further embodiments of the invention, the lens coating layercomprises a reactive species that reacts with an indicator in the fluidlayer 207. For example, the lens coating layer 205 comprises a basematerial, such as sodium bicarbonate, which is leached from the lenscoating layer 205 or is dissolved into the fluid layer 207 from the lenscoating layer 205. The fluid layer 207 comprises a pH indicator and anacid material and when a sufficient amount of base material is dissolvedinto the fluid layer 207, then the acid material is naturalized and thepH indicator changes color, indicating the passage of a duration oftime.

In still further embodiments of the invention, a timing device 200comprises a diffusion material 209. When the device 200 is activated,the diffusion material 209 begins to diffuse through the fluid layer207, as indicated by the arrows 215. When the diffusion material 209reaches the lens coating layer 205, the diffusion material 209 reactswith the lens coating layer 205 to provide a color change, dissolve thelens coating layer 205 and react with the indicator layer 203, or anycombination thereof, to indicate the passage of a duration of time.

Still referring to FIG. 2, a timing device 200, in accordance with theembodiments of the present invention also comprises an attaching means213 for attaching the timing device 200 to a product or an object (notshown). The attaching means 213 is any suitable attaching means, and insome embodiments, comprises an adhesive layer for sticking the device200 onto the product or object.

Now referring to FIG. 3A, a timing system 300, in accordance with amethod of the invention, is fabricated in parts 310 and 320. A firstpart 310 of the system 300 comprises a first reactive region 307 formedon a suitable base 301. A second part 320 of the system 300 comprises asecond reaction region 305 formed on a clear lens 303. One or both ofthe parts 310 and 320 comprise adhesive rings 311 and 309. To actuatethe system 300, the parts are brought together such that the firstreactive region 307 and the second reactive region 305 are eclipsed andin contact with each other. The adhesive rings 311 and 309 hold thefirst part 310 and the second part 320 together with the reactiveregions 305 and 307 eclipsed and in contact. While in contact with eachother, the first reactive region 307 and the second reactive region 305,undergo a chemical, physical or electrochemical process which alters thevisibility of the base 310 through the lens 303, as described above.Each of the parts 310 and 320 of the system 300, in accordance withfurther embodiments of the invention, comprise a protective covering(not shown), such as a cellophane, which acts protective of the reactiveregions 307 and 305, and is removed prior to use.

Now referring to FIG. 3B, a system 320, in accordance with theembodiments of the invention, is formed by fabricating a plurality offirst reactive regions 322 on a first piece of tape 321 and a pluralityof second reactive regions 324 on a second piece of tape 323. In someembodiments, the tapes 321 and 323 have perforations 326 and 328 betweeneach of the first reactive regions 322 and the second reactive regions324. In some embodiments, the tapes 321 and 323 are configured to bedispensed from a roll dispenser (not shown) or any other suitabledispenser. The dispenser can be dispenser configured to attach to ahousehold appliance using a magnet or any other suitable attachmentmeans.

In use, an activated device is formed by removing a first part 327comprising a first reactive region 322 and a second part 329 comprisinga second reaction region 324 from the tapes 321 and 323 through theperforations 326 and 328, respectively. The first part 327 and thesecond part 329 are then combined with the first reactive region 322 andthe second reactive region 324 eclipsed and in contact, as explained indetail above.

Now referring to FIG. 3C, in accordance with alternative embodiments ofthe invention, a system 340 comprises a plurality of first reactiveregions 342 and second reactive regions 344 formed in an alternatingfashion on single piece of tape 343. In use, an activated device isformed from a section 349 comprising a first reactive region 342 and asecond reactive region 344 that is separated from the tape 343 through aperforation 348. The section 349 is then folded over onto itself througha seam 346, such that the first reactive region 342 and the secondreactive region 348 are eclipsed and in contact with each other. WhileFIG. 3C, shows the first reactive regions 342 and the second reactiveregions 344 being formed in an alternating fashion on single piece oftape 343 such that an active device is formed by folding one of thefirst reactive regions 342 and one of the second reactive regions 344 inan end-to-end fashion, it will be clear to one skilled in the art that asystem can alternatively be formed on single piece of tape with firstreactive regions and second reactive regions formed in rows, such thatan active device is formed by folding one of the first reactive regions342 and one of the second reactive regions 344 in a side-to-sidefashion. It will be appreciated that forming first and second reactiveregions using other configurations is also possible in accordance withthe present invention.

FIG. 4A shows a cross sectional view of a timing device 400, inaccordance with the embodiments of the invention. As describedpreviously, the device 400 comprises a lens 405 and a base 401. Thedevice 400 also comprises an optical medium with one or more fluidlayers 411 and 411′ and a membrane structure 412 therebetween. Thedevice 400 further comprises a lens coating layer 403 and a reactivematerial 413 that is capable of reacting with the lens coating layer403. To activate the timing device 400, the membrane structure 403 isruptured allowing the reactive material 413 to mix with the fluid layers411 and 411′ and react with the lens coating layer 403, therebyindicating the passage of a duration of time.

Referring now to FIG. 4B, a timing device 420, in accordance withfurther embodiments of the invention, comprises a lens 425, a metal basestructure 421 and an ionic fluid medium or electrolyte 431,therebetween. The metal base structure 421 is formed from a first metallayer 424 with a first reduction potential and a second metal layer 422with a second reduction potential that is substantially different fromthe first metal layer 424. The device 420 also has metal lens coatinglayer 423 with a reduction potential that is also substantiallydifferent from the first metal layer 424, but can be the same or nearlythe same as the reduction potential of the second metal layer 422. Toactuate the device the metal lens coating layer 423 and the second metallayer 422 are placed in electrical communication with each other. Thepotential difference between the first metal layer 424 and the secondmetal layer 422 will drive a current to flow and cause the metal lenscoating layer 423 to become depleted over time, and plate out over thefirst metal layer, thereby indicating the passage of a duration of time.

In accordance with the embodiments of the invention, a timing device 420comprises a lens 425 formed from a transparent polymer, such aspolyester, or from a conductive polymer that is coated with a metal lenscoating layer 423, such as aluminum. The timing device 420 furthercomprises a base structure 421 and a second electrode material 422. Thesecond electrode material 422 can be any metal with a reductionpotential that is different from a reduction potential of the firstelectrode material 423. Alternatively, the second electrode material 422can be any metal with a reduction potential that is the same as thereduction potential of the first electrode material 423, when the device420 is being operated as an electrolytic cell (viz. has a batterystructure 421 or other source of electrons to drive the reduction andoxidation process). Between the first electrode material 423 and thebase structure 421 is a colored electrolyte 431. When the timing device420 is activated, the first electrode material 423 is depleted from thetransparent lens 423 and the colored electrolyte 431 becomes visible,thereby indicating the passage of the duration of time.

In yet further embodiments of the invention, a metal screen (not shown)is in contact with one or both of the metal lens coating layer 423 andthe second electrode material 422, to help ensure uniform depletionand/or plating of the electrode materials.

In still further embodiments of the invention, a timing device 420comprises an electrolyte 431 with an indicator that changes when thedevice 420 is activated, such as described above, and theelectrochemical cell generates a sufficient concentration of an ion or apH altering species within the electrolyte.

In accordance with yet further embodiments of the invention, a timingdevice 440 is coupled to a circuit 450, as shown in FIG. 4C. The device440 comprises a lens 443, a metal base 441, a reactive medium 451 and alens coating layer 445. The ionic reactive medium 451 is capable ofdepleting or dissolving the lens coating layer 445, either chemically orelectrochemically as explained previously, when the device 440 isactivated. After the device is activated and the lens coating layer 445is sufficiently depleted or dissolved, the ionic reactive medium 451provides an electrical path to close the circuit 450 between the leads447 and 448. The circuit 450, in accordance with the embodiments of theinvention, comprises a battery 446 and a piezo-electric element 449 thatgenerate an audible signal when the device 440 expires and the circuit450 is closed.

In still further embodiments of the invention, a timing device comprisesa galvanic cell or an electrolytic cell, wherein one or moreelectrochemically active materials between a transparent lens and abase, such as metal ions and/or electrodes, are configured to be platedout or depleted and alters the visibility of the base through the lensand indicating the passage of a duration of time. Where a timing deviceis an electrochemical-based timing device, an actuator switch mechanismcomprising electrical contacts can be used to actuate the device. Thetiming device, in accordance with still further embodiments of theinvention, is in electrical communication with a thermosensor (notshown), wherein the thermosensor instructs the actuator switch to closea circuit between electrode elements of a galvanic or electrolytic cellwithin a range of temperatures.

Referring to FIG. 5, in accordance with yet further embodiments of theinvention, a device comprises a film 500 with a plurality of zones(shown as 1-10). The zones can be arranged in any geometric pattern, butin some embodiments, are arranged in a linear fashion from a first end510 to a second end 520 of the film 500. The zones are configured tochange color at different rates and, therefore, provide an indication ofthe passage of a range of times. For example, when each of the zonesrepresents one hour, then the film 500 as shown, indicates the passageof approximately 7 hours. In approximately one more hour, the next zonewill change color and indicate the passage of approximately 8 hours.

Still referring to FIG. 5, each of the zones, in accordance with theembodiments of the invention, comprises a photographic, chemical and/orelectro-chemical material, as described in detail above. When the zones(shown as 1-10) comprise photographic materials, the zones can be madeto have different rates of reaction by using photographic materials withdifferent sensitivities to heat, light and/or developer and/or byvarying the thickness of diffusion layers deposited over each of thezones, such as described below. In accordance with an embodiment of theinvention, the zones are made to have different rates of reaction and/orsensitivity to a developer by pre-treating the zones to a range ofdifferent light and/or heat exposures, wherein the zones with longerexposures will develop and change color faster than zones with shorterexposures after being activated.

Still referring to FIG. 5, when the zones (shown as 1-10) comprisechemical and/or electro-chemical material(s), as described in detailabove and in accordance with the embodiments of the invention, the zonesare made to have different rates of reactivity and/or sensitivity.Accordingly, each zone has a different expiration time and indicatedpassage of a different amount of time and the zones viewed collectivelyindicate passage of a total time. This embodiment has particularapplications for managing inventories of food items in a householdrefrigerator by indicating how long the food items have been in therefrigerator, regardless of whether or not the food items have spoiledor aged past a freshness date.

FIG. 6 is a cross-sectional representation of a section of timing film600, in accordance with the embodiments of the invention. The section oftiming film 600 is formed by coating or depositing a photographic layer605, which can include silver, silver halide, gelatin, cellulose, fattyacids, developers or combinations thereof, onto a base structure 603. Insome embodiments, the base structure 603 is formed from a polymericmaterial, such as polyester, and can also include an adhesive layer (notshown) for attaching the section of timing film 600 to a consumerarticle (also not shown).

Still referring to FIG. 6, the section of film 600, in accordance withthe embodiments of the invention, further comprises a diffusion layer615 comprising a diffusion material and a developer layer 611 comprisinga developer. The diffusion material is any material that will allow thedeveloper in the developer layer 611 to migrate to the photographiclayer 605 causing the photographic layer 605 to change color or darkenand indicate the passage of time. Suitable diffusion materials include,but are not limited to, gelatin, cellulose and combinations thereof.

In accordance with still further embodiments of the invention, thesection of film 600 further comprises a barrier layer 613 that can bepulled out or removed to activate the device and allow the developerlayer 611 to diffuse through the layer 615 and cause the photographiclayer 605 to change color or darken and indicate the passage of time.Alternatively, the photographic layer 605 and the developer layer 611are formed as separate parts that can be brought together to activatethe device, as explained in detail above with reference to FIGS. 3A-C.

FIG. 7A shows a cross-sectional view of a reactive region 700 of atiming device. The reactive region 700 of the timing device reacts toproduce a visual change and indicate a passage of time, as explainedabove. The timing device can also include a lens and a base (not shown),such as described with reference to FIGS. 1A-B and FIG. 2.

Still referring to FIG. 7A, in accordance with the embodiments of theinvention, the reactive region 700 comprises a first reactive portion701 and a second reactive portion 703. The first reactive portion 701and the second reaction portion 703 are, for example, metals withdifferent reduction potentials that are capable of participating in thegeneration of an electrical potential in a galvanic cell or anelectrolytic cell, as described previously. The reaction region 700 canalso include an electrolyte 705 and electrical connections 711 and 713which allow current to flow between the first reactive portion 701 andthe second reaction portion 703 and generate a visual change to indicatea passage of time, as described above. In accordance with theembodiments of the invention, the reactive region 700 further comprisesa compensating element 707 which is electrically coupled to the firstreactive portion 701 and the second reactive portion 703 to compensatefor changes in electrical potential and rates of reactions that can, andgenerally do, occur as a result of changes in temperature. Thecompensating element 707 can increase or decrease the rate thatelectrons flow through the electrical connections 711 and 713 with achange in temperature and the response to changes in temperature willdepend on the application at hand. Suitable compensating elementsinclude, but are not limited to, varistors, thermistors (both positivetemperature compensating and negative temperature compensatingthermistors) and/or combinations thereof. A varistor refers to anelement that drops in resistance as the applied voltage across thevaristor is increased. A positive temperature compensating thermistorrefers to an element that drops in resistance as the temperature of thethermistor increases. A negative temperature compensating thermistorrefers to an element that increases in resistance as the temperature ofthe thermistor increases.

Now referring to FIG. 7B, a timing device 720, in accordance theembodiments of the invention, comprises a lens 725, a metal basestructure 721 and an ionic fluid medium or electrolyte 731,therebetween. The metal base structure 721 is formed from a first metallayer 724 with a first reduction potential and a second metal layer 722with a second reduction potential that is substantially different fromthat of the first metal layer 724. The device 720 also has metal lenscoating layer 723 with a reduction potential that is also substantiallydifferent from that of the first metal layer 724, but can be the same ornearly the same as the reduction potential of the second metal layer722. To actuate the timing device 720 the metal lens coating layer 723and the second metal layer 722 are placed in electrical communicationwith each other through connectors 731 and 733. The potential differencebetween the first metal layer 724 and the second metal layer 722 willdrive a current to flow and cause the metal lens coating layer 723 tobecome depleted over time, and plate out over the first metal layer 724,thereby indicating the passage of a duration of time. Between theelectrical connections 731 and 733 there is a compensating element 707,such as described above, that changes resistance in response to changesin applied potential, current flow, temperature or a combinationthereof, thus making the timing device either more stable to the changesin temperature or more sensitive to the changes in temperature.

In accordance with yet further embodiments of the invention, a timingdevice utilizes an electrochromic material. An electrochromic materialrefers to a material that changes color when the composition of thematerial is changed by use of an electrochemical cell or other voltagesource. Electrochromic materials often exhibit reversible color changesand can be switched between two or more color states by reversing thepolarity of an applied potential of a layer comprising the material thatis in contact with an ion or metal ion source, as described in detailbelow. A number of materials exhibit electrochromism, including but notlimited to, tungsten oxide, molybdenum oxide, titanium oxide, niobiumoxide, iridium oxide and rhodium oxide, to name a few.

FIG. 8A shows an exemplary reaction for electrochromic tungsten oxide803, which is transparent. To change the color of the tungsten oxide803, electrons 804 are provided from a cathodic site of the device whichreduces ions or metal ions (M+) from an ion source 802. The reduced ionsor atoms then combine with the tungsten oxide 803 to form ametal-tungsten oxide complex or structure 805 which is blue. The processcan be reversed by oxidizing the metal-tungsten oxide complex orstructure 805 at an anodic site of the device.

FIG. 8B shows a schematic representation of a multi-layeredelectrochromic device 800 in accordance with the embodiments of theinvention. The electrochromic device 800 comprises containment layers821 and 833, at least one of which is transparent so that color changesin an electrochromic layer 825 can be observed. The device 800 also haselectrode layers 823 and 829, an electrochromic layer 825 and a metalion source layer 827 therebetween. The electrochromic layer 825comprises one or more electrochromic materials and the metal ion sourcelayer 827 comprises metal ions 822, such as those described above withrespect to FIG. 8A. In operation, an electrical potential is appliedacross the electrode layers 823 and 829 and electrons 824 and 826 flowinto the electrochromic layer 825 from the electrode layer 829. Metalions 822 migrate from the metal ion source layer 827 into theelectrochromic layer 825 where the metal ions are reduced by theelectrons 824 and combine with an electrochromic material to produce acolor change within the electrochromic layer 825. The electricalpotential can be applied across the electrode layers 823 and 829 using abattery 832 that is electrically coupled to the electrode layer 823 and829 through electrical connections 828 and 830 and one or moreconductive layers 831. As described previously, the process can bereversed by reversing the polarity of the battery 832.

Now referring to FIG. 9A, a timing device 900, in accordance with theembodiments of the present invention, comprises a layered electrochromicstructure 916, which can include transparent constrainment layers 901and 907 with an electrochromic layer 905 therebetween, similar to thatdescribed with reference to FIG. 8B. The timing device 900 can alsoinclude a base structure 903 that is viewable through the layeredelectrochromic structure 916 when the electrochromic layer 905 is in atransparent color state. In some embodiments, the device 900 alsoincludes a driver circuit 910 that includes a voltage source 926 (FIG.9B) that is electrically coupled to the electrochromic layer 905 throughelectrical connections 911 and 913. When an electrical potential isapplied across the electrochromic layer 905, the electrochromicstructure 916 switches from transparent and opaque and/or colored orswitches for opaque and/or colored to transparent depending on thepolarity of the electrical potential that is applied.

Now referring to FIG. 9B, the driver circuit 910, in accordance with theembodiments of the invention, comprises a timing circuit 920, such as adigital timing circuit and a battery structure 926 for providing theelectrical potential. The battery structure 926 comprises any suitableelements capable of generating an electrical potential sufficient tochange the color state of the electrochromic layer 905 (FIG. 9A).Suitable battery elements include, but are not limited to, a firstelectrode structure 921, a second electrode structure 923 and anelectrolyte structure 922. In operation, the timing circuit 920 can actas a switch that maintains an open circuit between the battery structure926 and the electrochromic layer 905 (FIG. 9A) for a prescribed periodof time and then closes the circuit between the battery structure 926and the electrochromic layer 905 after the prescribed period of timecausing a color change in the layered electrochromic structure 916 (FIG.9A).

In accordance with yet further embodiments the invention, the drivercircuit 910 is programmable and can be programmed to switch or changethe color state of the layered electrochromic structure 916 in a rangeof prescribed times that are selectable by the user and/or manufacturer.In still further embodiments of the invention, the layeredelectrochromic structure 916 is divided into zones, wherein the zonesare activated in a range of prescribed times and the zones individuallyor collectively change color to indicate the passage of time or thepassage of a range of times, such as previously described with referenceto FIG. 5.

In accordance with still further embodiments of the invention, a timingdevice comprises an electrochemical cell configuration, such asdescribed with respect to FIGS. 4B-C and 7B, wherein the timing devicecomprises a plurality of sub cells or zones that individually orcollectively indicate the passage of time or the passage of a range oftimes, such as previously described with reference to FIG. 5. Forexample, a timing device is configured with a plurality of sub cells orzones that each includes a first set of electrodes formed from a firstelectrode material. The first electrodes are electrically isolated fromeach other and are in electrical communication with a second electrodeor second set of electrodes formed from a second electrode materialthrough resistors having a range of different resistivities.

Now referring to FIG. 10 showing a schematic representation of a timingdevice 250 with an electrochemical structure 252 and an indicating layer257. The electrochemical structure 252 can be configured in any numberof different ways, such as described above, but in some embodiments,comprises an indicating electrolyte 253, a top electrode 255 and abottom electrode 251. In operation, the device 250 is activated throughan activating mechanism (not shown) and the top electrode 255 isdepleted or partially depleted. The indicating electrolyte 253 thencontacts the indicating layer 257 and changes the appearance of theindicating layer 257. For example, the indicating electrolyte 253 iscolored and the indicating layer 257 is formed from a porous or anabsorbent material, such as cellulose. When the top electrode 257 isdepleted, or partially depleted, the indicating electrolyte 253 isabsorbed into the indicating layer 257 providing a visual indication ofa passage of time. The timing device 250 can also include a protectivecover 258 or clear lens, such as described previously. The indicatinglayer 257 helps to provide a uniform visual indication of the passage oftime, even when depletion, or partial depletion, of the top electrode255 is not uniform. The timing device 250 can also be equipped with acompensating element (not shown) and any other number of auxiliaryelements, such as described with reference to the previous embodiments.Further, it is understood that the timing device 250 can besectionalized or compartmentalized to indicate the passage of a range oftimes, also described with reference to previous embodiments.

Referring now to FIG. 11 showing a schematic representation of timingdevice 105 comprising a solid-state electrolyte 151 that is sandwichedbetween electrode structures 153 and 155. The electrode structures 153and 155 can be formed from any number of different materials andcombinations of materials, including metal coated polymer. For example,the solid-state electrolyte 151 comprises one or more materials selectedfrom the group of silver halide (e.g. AgI and RbAg₄I₅), silver selenide(e.g. Ag₂Se), sodium ion complexes (e.g. sodium β-Aluminum and NASICON),lithium ion complexes (e.g. LiCoO₂, LiNiO₂ and LiMnO₂), oxides (e.gcubic stabilized ZrO₂, β-Bi2O₃, and defect Perovskites) and Fluoride ioncomplexes (e.g. PbF₂, BaF₂, SrF₂ and CaF₂). In operation, the electrodestructures 153 and 155 are electrically coupled through an activatingmechanism 157 that is a switch, a timing circuit or any other activatingmechanism. Electrically coupling the electrode structures 153 and 155results in the depletion or partial depletion of one or more electrodematerials and provides an indication of the passage of time. The timingdevice 150 with the solid-state electrolyte 151 can, in accordance withthe embodiments of the invention, be formed as a plurality of sub cellsor zones that individually or collectively indicate the passage of timeor the passage of a range of times, such as previously described withreference to FIG. 5.

Referring now to FIG. 12, a solid-state timing device 350 is formed inparts with a first electrode structure 352 formed on a first piece of asubstrate 351 and a second electrode structure 354 formed on a secondpiece of the substrate 351′. The first electrode structure 352 comprisesa first metal layer 359 and a solid-state electrolyte layer 361 formedthereon. The second electrode structure 354 comprises a second metallayer 355, wherein the first metal layer 359 and the second metal layer355 are formed from metals with different reduction potentials, such asdescribed in detail above.

Still referring to FIG. 12, the first piece of the substrate 351 and thesecond piece of the substrate 351′ can be formed from any number ofdifferent materials or combinations of materials, such as glass, metalor plastic. In some embodiments, the first piece of the substrate 351and the second piece of the substrate 351′ are formed from plastic, suchas polyester or another similar transparent material. In accordance withfurther embodiments of the invention, removable protective layers 353and 357 are formed over the first electrode structure 352 and the secondelectrode structure 354, respectively. In operation, the protectivelayers 353 and 357 are removed and the first piece of the substrate 351and the second piece of the substrate 351′ are folded along a fold orperforation 363 as indicated by the arrow 365, such that the firstelectrode structure 352 and the second electrode structure 354 makeohmic contact and actuate the timing device 350. As described in detailabove, depletion of at least one of the metal layers 359 and 355provides a visual indication of a passage of a duration of time throughone of the first piece of the substrate 351 and the second piece of thesubstrate 351′.

In accordance with still further embodiments of the invention, thetiming device 350 comprises a switch mechanism (not shown), acompensating element (not shown) and/or an indicator layer (not shown),such as described above. Further, one or both of the first and secondelectrode structures 352 and 354 can be divided into sub-cells or zones,such that the sub-cells or zones collectively provide a visualindication of a passage of a range of durations of time.

Referring now to FIGS. 13A-B, a timing device 1300 includes, inaccordance with the embodiments of the invention, an electrode structure1304 that has a grid array architecture. The timing device 1300 includesan electrolyte layer 1315 that is formed or placed on a suitable baselayer 1321. The base layer 1321 is formed from any suitable materialincluding, but not limited to, plastic, glass, metal and combinationsthereof. On top of or over the electrolyte layer or deposited onto thelens layer 1323, is the electrode structure 1304. The electrodestructure 1304 includes an anode layer 1301 and a cathode layer 1302. Insome embodiments, the cathode layer 1302 does not contact theelectrolyte layer 1315 and is separated from the electrolyte layer 1315by an insulating layer 1319. The anode layer 1301 is in contact with theelectrolyte layer 1315. The electrolyte layer 1315 is formed from asolid-sate material, a liquid material, a gel material and/or asemi-solid paste material or a salt type electrolyte.

Still referring to FIGS. 13A-B, a thermistor layer 1305 may beincorporated into an anode layer and is preferably formed along side ofthe main or depletable anode layer 1301 and the cathode layer 1302.Also, an array of cathode structures 1313 and 1313′ are formed over theanode layer 1301 and the thermistor layer 1305 to provide electricalcontacts between the thermistor layer 1305 and the anode layer 1301.There is also at least one contact trace 1317 between the cathode layer1302 and the thermistor layer 1305 allowing for electrical conductivity.The anode layer 1301, the cathode layer 1302, the thermistor layer 1305,the cathode trace structures 1313 and 1313′ and the contact trace 1317can be formed using any suitable technique known in the art including,but not limited to, vapor deposition, sputtering and micro-printingtechniques.

The timing device 1300 with a grid array architecture preferablyincludes a mechanism for activating the timing device, such as describedabove. When the timing device 1300 is activated, the anode layer 1301begins to deplete in a direction away from the cathode layer 1302, asindicated by the arrow 1311, thereby exposing sequentially positionedcathode structures 1313 and 1313′. Newly exposed cathode tracestructures provide points of unequal electrical potential causingcurrent to flow. As anode material depletes away from the newly exposedtrace, distance between the leading edges of each increases, whichincrease resistance and decreases rate of depletion until a new cathodetrace is exposed once again and thus control the rate that the anodelayer 1301 is depleted. The number, the spacing, the thicknesses andgeometries of the cathode trace structures 1313 and 1313′ as well as theanode layer 1301, the cathode layer 1302 and the thermistor layer 1305,are designed or tailored for the application at hand. Further, thematerial used to form the thermistor layer 1305, in accordance with theembodiments of the invention, is selected to regulate the electricalcurrent or overall depletion rate of the anode layer 1301 to betemperature independent. As described in detail above, a timing device,such as the timing device 1300, includes a protective lens or window1323 through which depletion of the anode layer 1301 is directly orindirectly is observed.

Referring now to FIG. 14, a timing device 1400 comprises an anode layer1401, a cathode layer 1412 and an electrolyte (not shown) attached to alens area 1415. As shown in FIG. 14, the anode layer 1401 and thecathode layer 1412 are positioned adjacent to one another along thelongitudinal axis of the timing device 1400. Upon activation of thetiming device 1400, the anode layer 1401 is depleted longitudinally awayfrom and perpendicular to the cathode layer 1412 as demonstrated by thearrow. Depletion of the anode layer 1401 occurs at a point nearest tothe cathode layer 1412 first and progresses longitudinally away from andperpendicular to the cathode layer 1412. Depletion of the anode layer1401 occurs at an initial rate which lessens as the anode layer 1401depletes away from the cathode trace 1412. In some embodiments, thedevice comprises multiple anode depletion patterns 1402 printed ordeposited onto the lens 1415 that are uncovered as depletion of theanode layer 1401 progresses.

Referring now to FIG. 15, a timing device 1500 comprises a grid arrayarchitecture. In accordance with this embodiment, the timing devicecomprises an anode layer 1501, an electrolyte (not shown) and aplurality of cathode trace structures 1513 that are reintroducedthroughout the timing device 1500. Upon activation of the timing device1500, the anode layer 1501 is depleted at a point nearest the firstcathode trace structure at the beginning of the timing device 1505 andprogresses in a direction longitudinally away from and perpendicular tothe first cathode trace structure 1513 to the second cathode tracestructure 1513′. The anode layer then depletes from the second cathodetrace structure 1513′ to the third cathode trace structure 1513″ and soon to each subsequent cathode trace structure. Depletion of the anodelayer 1501 occurs at an initial rate, wherein the rate of depletion ofthe anode layer 1501 decreases as the anode layer 1501 progressesfarther from the first cathode trace structure 1513 to the secondcathode trace structure 1513′. When the anode layer 1501 has depleted tothe second cathode trace structure 1513′ the depletion of the anodelayer 1501 once again occurs at the initial rate, and so on to eachsubsequent cathode trace structure. In some embodiments, the cathodetrace structures 1513 are reintroduced throughout the timing device atevenly spaced intervals. In these embodiments, the anode layer 1501overall depletes at a constant rate throughout the timing device asshown by the progression from 1513 to 1513″. In some embodiments, thecathode trace structures 1513 are introduced throughout the timingdevice 1500 at unevenly spaced intervals. In some embodiments, thecathode trace structures 1513 are reintroduced throughout the timingdevice at progressively closer intervals 1524 such that there is anacceleration of the depletion of the anode layer 1501 as the timingdevice 1500 nears expiration.

In some embodiments, a timing device is activated when a quantity ofelectrolyte (not shown) contacts a main body of electrolyte (not shown)of the timing device 1500 such that an electrical circuit is completed.In these embodiments, the timing device 1500 is manufactured with ananode layer 1501, an electrolyte and a plurality of cathode tracestructures 1513 reintroduced throughout the timing device 1500. Thetiming device 1500 is manufactured in the closed position with aquantity of electrolyte only partially deposited just short ofcontacting the cathode layer. The timing device 1500 further comprises aprotective reservoir containing a small amount of electrolyte (notshown) molded to the cathode layer and protruding outward. The timingdevice 1500 is activated when a consumer applies pressure to theprotrusion thereby breaking the protective barrier and depositing thesmall quantity of electrolyte into contact with the main body of theelectrolyte and activating the timing device 1500.

The timing device has applications for marking when any number ofdifferent events need to take place and/or for timing the duration ofany number of different events. For example, the timing device hasapplications for indicating when perishable materials have expired andneed to be thrown out, indicating the age of inventory and managing whenthe inventory needs to be rotated, tracking a deadline and a host ofother time and/or temperature dependent events. One advantage is thatthe timing device is able to be fabricated in two or more reactiveparts, wherein the device is not activated, or made sensitive to theenvironment (such as temperature), until the parts are electricallycoupled together, as explained in detail above. Accordingly, the shelflife of the timing device prior to use is enhanced and the sensitivityof the device to environmental conditions prior to use is reduced.

The present invention has been described in terms of specificembodiments incorporating details to facilitate the understanding of theprinciples of construction and operation of the invention. As such,references, herein, to specific embodiments and details thereof are notintended to limit the scope of the claims appended hereto. It will beapparent to those skilled in the art that modifications can be made inthe embodiments chosen for illustration without departing from thespirit and scope of the invention.

1-26. (canceled)
 27. A timing device comprising a group of isolatedelectrochemical depletion zones grouped together in order tocollectively indicate a passage of time.
 28. The timing device of claim27, wherein the timing device comprises one or more depletion patternsthat are uncovered as depletion of the timing device progresses.
 29. Thetiming device of claim 27, wherein the timing device comprises an anodelayer, a cathode layer and an electrolyte.
 30. The timing device ofclaim 29, wherein the timing device comprises a plurality of cathodelayers introduced throughout a length of the timing device.
 31. Thetiming device of claim 27, wherein each of the depletion zones areconfigured to expire at a constant rate.
 32. The timing device of claimof claim 27, wherein the depletion zones are configured to expire atvariable rates.
 33. The timing device of claim 27, wherein the timingdevice is configured such that there is an acceleration of the depletionof the timing device as the timing device nears expiration.
 34. Thetiming device of claim 27, wherein the timing device comprises anactivator for activating the timing device.
 35. A timing systemcomprising: a. an activator for activating the timing system; and b. aplurality of isolated electrochemical depletion zones positionedadjacent along an axis of the timing system at evenly spaced intervalsin order to collectively indicate a passage of time.
 36. The timingsystem of claim 35, wherein the timing device comprises one or moredepletion patterns that are uncovered as depletion of the timing deviceprogresses.
 37. The timing system of claim 35, wherein the timing devicecomprises an anode layer, a cathode layer and an electrolyte.
 38. Thetiming system of claim 37, wherein the timing device comprises aplurality of cathode layers introduced throughout a length of the timingdevice.
 39. The timing system of claim 35, wherein each of the depletionzones are configured to expire at a constant rate.
 40. The timing systemof claim 35, wherein the depletion zones are configured to expire atvariable rates.
 41. The timing system of claim 35, wherein the timingdevice is configured such that there is an acceleration of the depletionof the timing device as the timing device nears expiration.
 42. A timingdevice comprising grid array architecture, comprising: a plurality ofindividual timing zones, each comprising a same timing distance andgrouped to collectively indicate a passage of time, and wherein one ormore depletion patterns are uncovered as the timing device depletes. 43.The timing device of claim 42, wherein the timing device comprises ananode layer, an electrolyte, and a plurality of cathode layersintroduced throughout a length of the timing device.
 44. The timingdevice of claim 42, wherein the timing device comprises a plurality ofcathode layers introduced throughout a length of the timing device. 45.The timing device of claim 42, wherein each of the depletion zones areconfigured to expire at a constant rate.
 46. The timing device of claim42, wherein the depletion zones are configured to expire at variablerates.
 47. The timing device of claim 42, wherein the timing device isconfigured such that there is an acceleration of the depletion of thetiming device as the timing device nears expiration.
 48. The timingdevice of claim 42, wherein the timing device comprises an activator foractivating the timing device.